Understanding small-scale processes controlling the bioavailability of organic contaminants to depsoit- feeding benthos

摘要

The bioavailable fraction of a sedimentary contaminant is defined as that portion present in the environment which is available for uptake by orgnaisms. This simple definition obscures a number of difficulties which impede our present ability to predict uptake and bioaccumulation of orgnaic contaminants by benthic deposit-feeding organisms. Mathematical modelling in combination with laboratory results demonstrates that physico-chemical equilibria are disrupted due to animal activity at demonstrates that physico-chemical equilibria are disrupted to animarl activity at smal spatial ( um m->mm) and temporal (sec->min) scales forcing consideration of short-term kinetic factors and casting doubt on simple equlibrium partitioning predictions. These anlayses further suggest that uptake by ingestion of contaminanted sediments may be the most importnat pathway for many infaunal benthos. Laboratory absorption efficiency experiments indicate a trophic uptake rate at least 20-30 times that predicted for pore water alone.